A word made up from bad Japanese translations of the word "Amazonesu." It's a combination of the word Amazon which refers to female warriors. And the suffix -ess which indicates female. So Amazoness is like saying "female Amazon" which means "female female warrior." I'm not quite sure why the Japanese use the word Amazonesu sometimes and Amazon other times. Unless it has something to do with Japanese not having plural words so they feel free to switch between the plural and singular. I believe Amazones is the plural of Amazon in Greek, but I'm not sure. It would probably be best to translate Amazonesu as Amazon or Amazons.
Have you ever seen the movie Amazoness in White?